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Maximum power output from USB ports?

Posted: Mon May 14, 2018 7:46 am
by Roland
What is the maximum power (W) the USB ports of X5000 can provide for peripherals? Is there any difference between the ports, or is there a common power pool for some of them?

Do the currently sold external USB harddisks (ordinary with moving parts, not SSD) generally work with X5000, without needing a powered hub? (Have tested only an old 300 GB Lacie and it seemed to work ok).

Re: Maximum power output from USB ports?

Posted: Mon May 14, 2018 2:26 pm
by tonyw
Each port can have its power (+5V) turned on or off by the controller. Most ports have a current limit of 500 mA (the required minimum for USB ports).

A mechanical HDD usually needs +12 V as well as +5 V, so I would be surprised if an external USB drive could operate without its own power supply. My 2 TB Seagate drives need 12V at 1.5A from an external plugpack.

An external hub usually provides power for the output ports (500 mA per port), so it would have a PSU for that purpose. I would not expect an external hub to provide any more than the standard 500 mA per port.

Re: Maximum power output from USB ports?

Posted: Mon May 14, 2018 11:52 pm
by daveyw
I have used an external 1 TB HDD plugged into my X5000's USB ports with no external power supply, no problem.

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 12:35 am
by tonyw
In that case, forget everything I said. It is clearly rubbish.

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 6:19 am
by daveyw
tonyw wrote:In that case, forget everything I said. It is clearly rubbish.
Ha, no, I wouldn't say that. :)

I guess it's theoretically not possible, and I'm probably running the risk of data corruption. I have an external CD drive that definitely requires an external PSU.

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 10:52 am
by broadblues
It really depends on the drive. I have a older thinkpad drive that will 'almost' work on the USB alone, but is significantly more reliable with the external powersupply attached.

Also some more modern drives come with 2 USB connectors to enable double powering from 2 sockets, they need to be on seperate hubs for this to be totally safe.

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 1:07 pm
by xenic
tonyw wrote:In that case, forget everything I said. It is clearly rubbish.
Not necessarily. I think the 12V requirement applies to most 3.5 inch hard drives but 2.5 inch laptop type hard drives only require 5V. I'm using 2.5 inch hard drives through an adapter connected to a SATA card with only 5V connected to the adapter. That works. The docs for the adapter state that 12V is also required if I use 3.5 inch hard drives.

EDIT: My 2.5 inch hard disks have no external power supply. The 5V power to my adapter comes directly from the power supply; which may be more robust than the 5V available on a USB port.

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 5:34 pm
by Roland
xenic wrote: Not necessarily. I think the 12V requirement applies to most 3.5 inch hard drives but 2.5 inch laptop type hard drives only require 5V. I'm using 2.5 inch hard drives through an adapter connected to a SATA card with only 5V connected to the adapter. That works. The docs for the adapter state that 12V is also required if I use 3.5 inch hard drives.

EDIT: My 2.5 inch hard disks have no external power supply. The 5V power to my adapter comes directly from the power supply; which may be more robust than the 5V available on a USB port.
According to the info I got from a major dealer, the 2,5" external drives are indeed powered only by the USB. They do not even have a connector for an external power supply. But the problem is that the USB 3.0 standard has higher power output (900mA/5V), and most drives are nowadays marketed as "USB 3.0". So, it is possible their consumption exceeds the USB 2.0 standard... But could it be that in a USB 2.0 port the power consumption is lower as also the transfer speed is much lower than with USB 3.0?

Re: Maximum power output from USB ports?

Posted: Tue May 15, 2018 7:25 pm
by xenic
@Roland
I bought my 2.5 hard drive cases seperately and they only have eSATAp and USB3 ports. I bought bare 2.5 hard drives for the cases. They work fine through my eSATAp (powered eSATA) adapters but If I plug them in with the USB3 cables that came with the cases, they get no power. I have found some 3.5 inch hard drives online that are labeled USB3/2 that have external power inputs if you use them with USB2.

Based on experience with my external drives, I don't think a USB3 external drive will get any power if you plug it into a USB port. I think you will need a USB3 drive with an external power power port. However, I could be wrong since I mounted SATA drives into seperately purchased cases.

Re: Maximum power output from USB ports?

Posted: Wed May 16, 2018 3:58 pm
by Petrol
Hi,
On my own experience, I've got 2.5" Hard drives (USB2) that works on AmigaOS4, USB3 ones don't, even if they are plugged on a USB2 switch. They are seen by the USB stack but they are not mounted into AmigaOS4. Otherwise under CFE, content of the disk can be se browsed!

Regards,
Petrol.